Recovery of sulphur



July 11, 1933. R, BA N E A 1,917,234

' RECOVERY OF SULPHUR Filed July 29, 1930 DUST COLLECTOR INVENTORS 7? M D F- BA con AnDISAACBENCOW/TZ BY G Q SM,M+GL

ATTORNEYS l atented July 11, l933 outrun STA TES PATENT "AOFFI'CET I RAYMOND BACON,- OF BRQNXVILLE,-.AND ISAAC BENCOWITZ, 013 NEW YORK, N. Y.;

SAID'BENCOWITZ ASSIGNOR SAID BALON RECOVERY OF SULPHUR Application filed July 29,

This invention relatesto the production of elemental sulphur, and has for its object re covery of sulphur from gases containing sulphur compounds such as sulphur dioxide. More particularly, the invention relates to an improved and economical process and apparatus for obtaining sulphur in the elemental form from roaster gases and the like.

ln the various processes which havebeen.

manner described hereinafter, by which, not

only is the high sensible heat of the roasting gases discharged from the furnace substantially retained, but additional heat is derived also from the furnacev itself.

The manner in which our invention is accomplished is as follows: V

In the diagram shown 1n the drawing, we

t the pyrites lines, and nozzles 4 for the introduction of air or other oxidizing gas are dis posed in the chamber in the neighborhood ofi thepoint of entry of the lines, to cause the oxidizing gas to intermingle therewith close to thepoint of entry.

At the bottom of the burner a grate 5 and cinder pit .6 are provided, from which the cinder may be removed in any well known the sensible heat ofinvention,'the ther- 1930. Serial No. 471,58Y.

manner, and at 7 is shown the outlet for the sulphur dioxide gases. I

The outlet 7 preferably leads to a well insulated dust collector 8, closely oining the burner, which collector may be of any well known mechanical type, for example, a ballic chamber, or may be of the electrostatic precipitation type. 7

'A conduit 9 for the roaster gases from the collector 8 connects tangentially with an annular reaction chamber 10 surrounding the burner shell 2, the outer wall of which chain ber should be highly insulating and may be constructed of fire brick or other suitable refractory material, capable of withstanding the heat and corrosive action of the gases involved. An inlet pipe '11 provides for the introduction ofreducing gas and the like into the chamber 10. A fan blowerl2is provided intermediate the collector 8 and the chamber '10, for providing properly regulated flow of the sulphur dioxide gases to the reaction chamber. I e

The gases from the reaction chamber 10 are discharged through pipe 13, which may be tangentially disposed to accelerate the discharge if-desired, and are conducted toappatherein and for other treatment.

The operation of our invention is as follows: I

The burner 1 is first brought up to a temperature considerably above the ignition point of the pyrites to be burned, and thereafter the fines are showered into the burner from the feeding device 3 accompanied by suitably controlled amounts of air or other; oxidizing gas introduced through a the nozzles t I The burning of the sulphur in the pyrites to sulhpur dioxide, is accompanied by the liberation of a very substantial amount of heat, and the temperature of the resulting gases in the burner is quite high, for example 900 tolOOO C.

Upon completion of the reaction, the burned pyrites cinder will drop into the cinder pit 6, from which it'may be removed in any well known manner. The hot sulphur dioxide gases are drawn off through the outratus for collecting the elemental sulphur let 7 by the suction created by the fan blower 12, the necessity for using which proceeds in part from the maintenance of a practically neutral pressure over the cinder outlet, which coincidentally retards the flow of gases through the outlet.

While practically all of the burned pyrites will pass off through the cinder pit 6, a certain proportion of very fine dust will however, be entrained in the sulphur dioxide gases resulting from such suspension-roasting operation. This dust is removed by the dust collector 8. y After leaving the dust collector 8, the hot sulphur dioxide gases are passed tangentially into the chamber 10, where they are brought in contact with the reducing gases introduced at 11. Natural gas, Water gas, producer gas are suitable reducinggases, and if desired, powdered carbonaceous material may be injected into the chamber 10 in lieu thereof.

The sulphur dioxide gases are already very hot, inasmuch as there has been no very material opportunity for their sensible heat to be dissipated in their short passage after leaving the burner. Thetemperature of the reducing gases will be very considerably elevated upon their being intermingled with i the hot sulphur dioxide gases.

The temperature of these gases is then further increased by the absorption of heat from the burner. To amplifythe amount of heat so absorbed, the thickness of the shell 2 of the burner may be reduced, the major insulation being provided in the outer wall of the chamber 10.

The reaction between the sulphur d ioxide and the reducing gases to yield elemental sulphur, is quite rapid and strongly exothermic, and with proper control, can be. made to proceed to practical completion with in the chamber 10. By the tangential introduction and discharge of the gases in the reaction chamber, the upwardly'spiralling current engendered thereby, renders the oath of flow and period of contact in this hot zone considerably longer than if straight vertical lip-draft were used, with obvious advantage to the cl'liciency of the reaction.

The gases leavmg the reaction chamber 10 through the outlet duct 13 may then be cooled in any suitable apparatus, for example a waste heat boiler, and treated in any well known manner to separate the sulphur therefrom, for example by electrostatic precipitation,absorption, or the'like. The residual gases may then be oxidized catalytically, or in any'other suitable manner well known in the art, to remove the objectionable COS and H S therein and to recover thesulphur from these and such other sulphur compounds, for example unreacted S0 as may be present therein.

Itis to be noted further, that the absorption of heat from the burner by the gases to be reacted, can be turned to advantage for simultaneously minimizing the very objectionable tendency towards scar formation which accompanies pyrites roasting. It is generally considered that this scarring is ascribable to the existence of too high a temperature, which results in fusion of the FeS remaining after the volatile sulphur atom of the FeS has been driven oil.

This fusion does not ordinarily occur until after the volatile sulphur is removed, nor does it occur when there is a quantity of Fe O present.

By reducing the temperature of the burner through the medium of heat absorption by these external sulphur dioxide and reducing gases, restraint may be placed upon the burners attaining a temperature, where fusion of the FeS takes place. This heat absorption is preferably applied over that portion of the burner where the material being roasted is mainlyin the FcS or scarring state, although, if desired, it may be extended throughout the furnace. n

This absorption to restrain the scarring is best, facilitated by reducing the thickness of the shell of the burner as much as possible, and particularly over that portion of the burner where scar formation principally takes place.

This absorption of heat from the burner by the sulphur dioxide and/or the reducing gases tov elevate their temperature for the purpose of accelerating their interaction and the simultaneous application of this absorption to the purpose of minimizing scar formation may be accomplished in severalman- In view of the rapidity with which the sulphur dioxide and the reducing gases interact, and the exothermic natureof that reaction, it is preferable that-such absorption by these gases take place before they are in reacting contact. This can be accomplished, for example, by passing either of these gases through a acket surrounding that por.

which scar formation is which should be passed about the scar formation zone will depend upon theconditions in and thenature oft-he respective gases. The sulphur while relatively hot, are of: considerable volume, and this will to an'extent compensate then. conducting the gas.

dioxide gases from the dust collector The selection of the one of tlie'two gases.

for the not so marked difference between their temperature and the temperature in the burner. Y

The reducing gases on the other hand, are at a Very substantially lower temperature, but the advisability of taking advantage of this much greater temperature differential depends considerably upon the particular reducing gas which is being used. i

The volume of producer gas and water gas utilized for reaction'with the sulphur dioxidegases is appreciably greater than the vol ume of natural gas 'required therefor, and consequently when'th'e former are used, the inclination would betowards their use as the heat absorbing gas as against the use of natural gas for such purpose.

The gas most advisable to selecthowever, will depend upon the particular operating conditions existent, and is readily determinableby one skilled in the art.

An alternative to the passage of only one of the reacting gases in contact with the scar formation zone is presented by the passage of both gases simultaneously through that zone, at such a high rate of flow that their extent of reaction and heat generation will not be detrimental. This can be accomplished by suitably increasing the speed of pressure or suction blowers, with the elimination of tangential feeds and other factors which tend to maintain the gases within the zone fortoo long a period. I

The hot intermingled gases discharged from the scar formation zone may then be permitted to react to substantial completion either in a separate chamber, or in a jacket surrounding a portion of the burner other than the scar formation zone.

Various other methods maybe used to carry out this operation aswill be apparent to one skilled-in the art.

The gases resulting from the reaction can then be treated in the manner previously noted for the separation of sulphur therefrom.

While in the foregoing we have noted the application of our invention to a shaft burner in the suspension roasting of'fines, the same is intended merely to be illustrative and is also applicable to mechanical or other burners, for burning either lump pyrites or pyrites smalls, as will be apparent to one skilled in the art.

The use of the dust collector 8 likewise is dictated by the particular type of roasting N operation with which it is connected, and in those operations where a practically slight amount of dust results, it maybe dispensed with if desired.

Likewise, down-draft of the gases in the roasting operation and Lip-draft of the heat absorbing gases externally of the burner,

may be replaced by the reverse arrangement with the provision of suitable draft-producing means where necessary.

WVe claim:

1. A process of producing elemental sulphur which comprises burning combustible sulphurous material with combustionsupporting material to produce sulphur dioxide, mixing with said sulphur dioxide a reagent capable of reducing it to elemental sulphur, and passing said mixture in noncontacting heat-exchanging relationship with said combustible and combustion-supporting materials during the process of combustion. V

'2. Aprocess of producing elemental sulphur which comprises burning combustible sulphide with combustion-supporting gas to produce sulphur dioxide, mixing with said sulphur dioxide, a gaseous reagent capable of reducing said sulphur dioxide to elemental sulphur, and passing said mixture in non-contacting heat-exchanging relationship with said combustible sulphide and combustion-supporting gas during the process of combustion. I

3. process of producing elemental sulphur which comprises burning sulphide ore withoxidizing gas to produce sulphur dioxide, mixing reducing agents with said sulphur dioxide while said sulphur dioxide contains a substantial proportion of the heat imparted to it during the ore burning process, and passing said mixture in non-contacting heat-exchanging relationship with the components of said burning operation during the burning process while the temperature thereof is higher than thetempe'rature' of said sulphur dioxide reducing agent mixture.

4-. A process of producing elemental sulphur which comprises burning combustible sulphurous material with combustion-supporting material to produce sulphur dioxide,

mixing with said sulphur dioxide a reagent capable of reducing it to elemental sulphur, and passing said mixture in a spiral path in non-contacting heat-exchanging relationship with said combustible and combustion-supporting materials during the process of combustion. 1

5. A process of producing elemental sulphur which comprises burning a combustible sulphurous material in a current of combustion-supporting gases to produce sulphur dioxide, mixing withsaid sulphur dioxide a reagent capable of reducing it to elemental sulphur, and passing said mixture in noncontacting heat exchanging counter-current relationship with the hot components of the combustion during the process of combustion.

6. A process of producing elemental sulphur which comprises burning combustible sulphurous material with combustion-supporting gas to produce sulphur dioxide, mix ing with saidsulphur dioxide a gaseous reagent capable of reducing it to elemental sulphur, and passing said mixture in a spiral path counter-current to and in non-contacting heat-exchanging relationship with the hot components of the combustion during the process of combustion. i

7. A process of producing elemental sulphur which comprises burning sulphide ore in air to oxide the sulphur therein to sulphur dioxide, mixingcarbonaceous reducing gas with said sulphur dioxide while the same contains a substantial proportion of the heat imparted to its during the ore-burning operation, and passing said mixture in non-contacting heat-exchanging relationship with the hot components of the ore-burning operation while the temperature thereof is higher than the temperature of said mixture of sulphur dioxide and'carbonaceous reducing gas.

8. A process of producing elemental sulphur which comprises burning pyrites in a I current of oxidizing gas to oxidize the sulpyrites is burned to sulphur dioxide which is subsequently reacted with a gas for reducin g it to elemental sulphur, the steps which comprise, passing one of said reacting gases in non-contacting heat-exchanging relationship with the hot components of the pyrites burning operation at that stage where the pyrites is in a state conducive to scar formation, said gas being at a temperature lower than that of the burning operation in said scar forming stage, and then mixing said heated gas With the other gas under conditions to produce elemental sulphur.

10. In a process of producing elemental sulphur from pyrites wherein the sulphur in the pyrites is burned to sulphur dioxide which is subsequently reacted with a gas for reducing it to elemental sulphur, the steps which comprise, passing said reducing gas in non-contacting heat-exchanging relationship with the hot components of the pyrites burning operation at that stage where the pyrites is in a state conducive to scar formation, said gas being at a temperature lower than that of the burning operation in said scar forming stage, and then mixing the heated reducing gaswith the sulphurdioxide gases from the burning operation under conditions to'produce elemental sulphur.

11. In a process of producingelemental sulphur from pyrites wherein the sulphur in the pyrites is burned to sulphur dioxide which is subsequently reacted with an agentfor reducing it to elemental sulphur, the steps which comprise passing the sulphur dioxide gases from the burning operation, in noncontacting heat-exchanging relationship with the hot components of the pyrites burning operation, at that stage in the burning opera tion where the pyrites is in a state conducive to scar formation, said gases being at a temperature lower than that of the burning operation in said scar forming stage, and then contacting the heatedsulphur dioxide gases with the reducing agent under conditions to produce elementalsulphur.

In testimony whereof we aflix our signatures.

Y RAYMOND F. BACON.

ISAAC BENCOW'ITZ.

Lin; 

